Methods of manufacturing shaped articles include powder additive manufacturing in which a process of partially sintering or melting metal powder spread over a plate is repeated to manufacture a shaped article, as disclosed in Patent Literature 1. In the manufacturing of a shaped article using powder additive manufacturing like this, the spread metal powder and the plate are joined by sintering or melting, so that the plate and the shaped article are integrally formed. Thus, it is necessary to separate the plate and the shaped article by post-processing after forming the shaped article. To separate the plate and the shaped article, cutting is performed using a cutting apparatus exemplified by a wire electrical discharge machining apparatus. For that purpose, a separated portion that is a cutting allowance to be cut by the cutting apparatus is provided between the shaped article and the plate.